toBytes

getInputFormat

This will be called during planning on the front end. This is the
instance of InputFormat (rather than the class name) because the
load function may need to instantiate the InputFormat in order
to control how it is constructed.

prepareToRead

Initializes LoadFunc for reading data. This will be called during execution
before any calls to getNext. The RecordReader needs to be passed here because
it has been instantiated for a particular InputSplit.

setLocation

Communicate to the loader the location of the object(s) being loaded.
The location string passed to the LoadFunc here is the return value of
LoadFunc.relativeToAbsolutePath(String, Path). Implementations
should use this method to communicate the location (and any other information)
to its underlying InputFormat through the Job object.
This method will be called in the backend multiple times. Implementations
should bear in mind that this method is called multiple times and should
ensure there are no inconsistent side effects due to the multiple calls.